Re: What's your favorite reaction?

I like surface-catalyzed reactions. I don't know why exactly, just that it's neat having kinetics happen on a 2-D plane as opposed to a 3-D volume.

Beyond that anything that's just neat to look at. For example, some of the biochemical reactions in cells with crazy long self-regulating mechanisms are neat to look at, even if I hated memorizing them back in school.

Re: What's your favorite reaction?

I like surface-catalyzed reactions. I don't know why exactly, just that it's neat having kinetics happen on a 2-D plane as opposed to a 3-D volume.

Hey that's a neat reaction context I hadn't thought of!!! I remember doing the kinetics for solution state. Wonder how this differs? You can't use concentrations, and you have one less degree of freedom to work with. Hmmmm...... interesting!

Beyond that anything that's just neat to look at. For example, some of the biochemical reactions in cells with crazy long self-regulating mechanisms are neat to look at, even if I hated memorizing them back in school.

When you say look at, you mean the reactions themselves? Or animations?

Re: What's your favorite reaction?

That was fun to watch!!! I didn't know about this reaction........ I'm trying to envision solvated electrons the same way we think about solvated protons..... bouncing around between water molecules. I'm just not sure exactly how they're being solvated though???? I don't think they can hydrogen bond.... Bouncing through vacant molecular orbitals????

Re: What's your favorite reaction?

Yup, "concentrations" for surfaces end up just being the number of available surface sites. Stoichiometricly, the quality of being a surface site is kinda like a new chemical element, so it's conserved. For example, if a surface site is either free or bound, then it's just.

The equations become more fun in more complex reactions, particularly when the total amount of surface sites is varying with time, e.g. if the solid is itself reacting off, changing its total surface area in the process. I just love systems of equations.

As for the crazy long biochemical reactions, yeah, I just meant looking at them conceptually. I never really got into any visual modeling software; it's something I'm always meaning to do but never end up making the time for. My favorite aspect is how self-regulation can be described in such simple terms but have the net effect of homeostasis. That kind of emergent complexity is just beautiful.

Re: What's your favorite reaction?

Just to keep the thread going, I'm nowadays on Citric Acid cycle or more famously Krebs Cycle.I think it's necessary for everyone to know this cycle, as it's really how we live.http://en.wikipedia.org/wiki/Krebs_CycleI rather found it hard to memorize all the steps, but finally managed! thank God!

Re: What's your favorite reaction?

I never quite warmed to chemistry in the same way I did for some other fields, but one reaction does spring to mind from one of my past hobbies (homebrewing), and that's the natural enzymatic conversion of the starches in malted barley into fermentable sugars. These enzymes become active when cereal grains are sprouted, and the modern malting process used for brewing barley is designed to help maximize the process.

Alpha amylase: it's most active in the 154-167F range, and creates longer chain sugars that are somewhat less fermentable, and yield a beer with a bit more body. This is the preferred enzyme when making full bodied ales (which is mostly what I was brewing).

Beta amylase: It's most active in the 130-150F range, and promotes the creation of shorter chain sugars that are more fermentable, and result in a drier beer. This is the preferred enzyme when making lighter bodied lagers.

For me, whenever I brewed a beer from all grain, it always seem magical when I added my hot water to the starchy malted barley, and it would slowly turn very sweet, all by itself. Recirculating the lot liquid through a deep bed of grains (which naturally stratifies into a filter of sorts), while maintaining the optimal conversion temperature range, is the core of what is called a "Recirculating Infusion Mash System" (RIMS) in the brewing industry. I jury rigged a small one for home use c.1996, which you can see below. With it, I was able to achieve PPG yield efficiencies in the 27-31 range (mostly around 29-30), which by homebrewing standards of the day was considered excellent.

The black gizmo is a food grade pump. The tall copper pipe is the heating coil, which I mounted to an upside down coffee can (which raised the height of the intake above the output of the food pump and also provided convenient storage for the power cord). Behind and left of the coffee can is the controller unit, which was nothing more than a pair of potentiometers ... one to control the speed of the pump, the other to control the heat of the coil. The setup was rather primitive ... nowadays, they make computerized controllers with digital thermometer probes, so it's much easier to use. I had to monitor and adjust by hand, with an analog thermometer.